Assessment of the performance of ventilated floor thermal storage systems

Ventilation of the building fabric is one method to achieve storage of heat and cold. A popular European method is to pass air through ducts within the floor and ceiling slabs. That air can either be at the outside air temperature or from the air-conditioning plant. In the former case, the intention is to transfer cold from night to day and in the latter to reduce peak loads by cooling the room surfaces and thus increase comfort via radiant cooling. The performance of such systems can be assessed by comparison with direct nighttime ventilation (say, through windows) and traditional air-conditioning systems operating during occupancy. The paper presents the development of a numerical model of a ventilated floor slab for use in a dynamic thermal model and the application of that model to a current design project. Energy consumption cannot be ignored; however, a complete analysis of the implication of storage systems would be a major paper. This paper therefore considers the main energy implications associated with slab storage systems.